Electrostatic discharge (ESD) is the sudden flow of electricity between two electrically charged objects caused by contact, an electrical short, or dielectric breakdown. ESD occurs when differently-charged objects are brought close together or when the dielectric between them breaks down. ESD can cause a range of harmful effects of importance in industry, including gas, fuel vapour and coal dust explosions, as well as failure of solid state electronics components such as integrated circuits (ICs). These can suffer permanent damage when subjected to high voltages. Manufacturers of integrated circuits usually take precautions to avoid ESD. ESD prevention can be part of the device itself and include special design techniques for device input and output pins. External protection components can also be used with circuit layout. In an IC chip, there are some high voltage electrostatic discharge (HVESD) protection circuits or low voltage electrostatic discharge (LVESD) protection circuits to prevent ESD damage. However, if some parasitic transistors exist in the IC chip, they may cause potential ESD risk in the high voltage design.
Like reference symbols in the various drawings indicate like elements.